Domain Functional Level

Question

Hi All,

I hope someone will be able to clarify.

We have a domain that has the majority of servers based on version W2008. The Domain Functional Level is W2008 for the Parent and child Domain.

Recently I saw that we have a few W2012 Domain Controllers that exist on the Parent Domain. I enquired and was told the the domain was in Dual Mode?

Since I always thought that the functional level can only hold servers that are the same as the Dom Func Level in our case W2008 I am a little confused by the actual setup.

Can someone explain what is meant by dual Mode? Any help would be appreciated.

Answer 1

Hello Czql5v,

The Domain Functional Level determines the available Active Directory Domain Services (AD DS) domain or forest capabilities and which Windows Server operating systems you can run on domain controllers in the domain or forest1. The Dual Mode refers to a specific functional level that allows for a mix of domain controllers running different versions of Windows Server in the same domain1.

In your case, it seems that your domain is operating in Dual Mode with a Domain Functional Level of Windows Server 2008. This means that you can have domain controllers running both Windows Server 2008 and Windows Server 2012 in your domain1. The functional level does not restrict the presence of domain controllers running newer versions of Windows Server, but it may limit certain features and capabilities that are specific to newer versions.

Hope this helps,

Fathia

Answer 2

Hello czql5v,

Thank you for posting in Microsoft Community forum.

To be honest, I've never heard Dual Mode domain this statement.

But for the functional level I understand the following:

Functional levels determine the available Active Directory Domain Services (AD DS) domain or forest capabilities. They also determine which Windows Server operating systems you can run on domain controllers in the domain or forest. However, functional levels do not affect which operating systems you can run on workstations and member servers that are joined to the domain or forest.

Ensure that all domain functional levels are equal to or higher than the forest functional level.

Ensure that all domain controller operating systems have are equal or higher than the domain functional level.

You Domain Functional Level is W2008, so you can add supported domain controller operating systems below in your domain.

• Windows Server 2022
• Windows Server 2019
• Windows Server 2016
• Windows Server 2012 R2
• Windows Server 2012
• Windows Server 2008 R2
• Windows Server 2008

Active Directory Domain Services Functional Levels in Windows Server | Microsoft Learn

I hope the information above is helpful.

If you have any question or concern, please feel free to let us know.

Best Regards,
Daisy Zhou

Answer 3

Thanks very much for your replies.

Fatiha thanks also for explaining further what dual mode is as I must admit had it heard of it previously, but understand what is meant and that some of the newer

Versions might not have full functionality if the forest level is lower than their version.

Regards

Answer 4

Hi Fatiha,

Yes it helped i have one follow up question not sure that you would know the answer but may be worth asking.

With the FFL at w2008 do you know what services will not be available on the w2012 DC. The reason I ask is that I work with GPO’s on a regular basis and was wondering if it might have an affect on the schema etc?

Regards.

Answer 5

Hello czql5v,

Thank you for your reply.

For different forest/domain functional level features, please check the information in the link below.
Active Directory Domain Services Functional Levels in Windows Server | Microsoft Learn

Q: With the FFL at w2008 do you know what services will not be available on the w2012 DC?
A: I think the features on Windows Server 2008 R2 forest functional level and above will not be available on the w2012 DC

Best Regards,
Daisy Zhou